The Cirrhipeds are well known under the names of _Barnacles_ and
_Acorn-shells_, being found attached to rocks, ships’ bottoms, and
pieces of timber which have been under the water for a length of time.
They also at times fix themselves on the shells of the larger Mollusca,
and on the backs of whales, tortoises, &c. These creatures, from their
singular formation, have often proved a stumbling-block in the way of
the systematic naturalist, who, from their anomalous characters, was
unable to refer them to any part of his system; and although their
true nature, which has more recently been discovered by a British
naturalist, was partially suspected by Lamarck, (without, however, any
definite idea on the subject,) we have still placed them immediately
after the Conchifera, although, as we shall presently show, they ought
more properly to be ranged with the Crustacea, that is, the crab and
lobster tribes, and in future systems this no doubt will be the case.
After noticing their resemblance in many respects to the Crustacea,
Lamarck thus expresses himself. “In fact, when I established the
CLASS of Crustacea, I formed the _first order_ of this class, (the
_Cirrhipeds_,) under the name of _sightless Crustacea_, but a few years
afterwards I separated them and placed them at the end of the Mollusca,
but this was no better. If, for example, we consider those characters
which furnish their most important organs, we shall find that the
Cirrhipeds, without any doubt, most nearly resemble the Crustacea,
for they have the same system of nerves, they have jaws analogous to
those of the Crustacea, and their tentacula resemble the antennæ of the
shrimps.” To prove that they really were Crustacea, was a task that
devolved upon a British naturalist, I. V. Thomson, Esq., a surgeon in
his Majesty’s forces. The manner in which this discovery took place, we
shall notice further on.
The Cirrhipeds have obtained their name from the hairy feelers, or
tentacula, with which they are provided; the name Cirrhipeda being
derived from two Latin words,—_cirrhus_, hair, and _pes_, the foot;
these appendages, being figuratively called feet, although they have,
in reality, but little relation to that organ of motion.
They have been separated into two orders; namely, _Cirrhipeda
pedunculata_, which are attached to any object by a tube of a leathery
nature, as, for instance, the Barnacle,—and _Cirrhipeda sedentaria_,
which are fixed directly to the rock, like the Acorn-shell.
_ORDER CIRRHIPEDA PEDUNCULATA._
(_Cirrhipeda with a Footstalk._)